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Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus.

Whissell PD, Cajanding JD, Fogel N, Kim JC - Front Neuroanat (2015)

Bottom Line: However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale.The reverse trend was observed for PV-GABA cells.The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto, Toronto ON, Canada.

ABSTRACT
Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

No MeSH data available.


Related in: MedlinePlus

Perisomatic interneuron balance and its relationship to cortical function. Cell balance was estimated using the delta score (D), which was the subtractive difference between CCK-GABA and PV-GABA cell percentage. Brain regions with D > 0 had more CCK-GABA cells, whereas regions with D < 0 had more PV-GABA cells. Moving right along x-axis of the graph, a decreasing D reflects a relatively increasing PV-GABA cell content. Regions of the primary sensory cortex or primary motor cortex (red) had negative D, indicating relatively higher PV-GABA cell content. Interestingly, secondary regions (green) had less negative D than their primary counterparts, indicating relatively lower PV-GABA cell content. For comparison, other non-motor and non-sensory cortical subregions are included (gray).
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Figure 7: Perisomatic interneuron balance and its relationship to cortical function. Cell balance was estimated using the delta score (D), which was the subtractive difference between CCK-GABA and PV-GABA cell percentage. Brain regions with D > 0 had more CCK-GABA cells, whereas regions with D < 0 had more PV-GABA cells. Moving right along x-axis of the graph, a decreasing D reflects a relatively increasing PV-GABA cell content. Regions of the primary sensory cortex or primary motor cortex (red) had negative D, indicating relatively higher PV-GABA cell content. Interestingly, secondary regions (green) had less negative D than their primary counterparts, indicating relatively lower PV-GABA cell content. For comparison, other non-motor and non-sensory cortical subregions are included (gray).

Mentions: As CCK- and PV-GABA neurons are thought to regulate pyramidal cell activity by distinct mechanisms (Freund, 2003; Freund and Katona, 2007), they may be specialized for certain cortical network activities. Within the cortex, information processing is known to differ substantially between the primary and secondary regions. Primary cortical regions (such as Aud1, V1, S1, and M1) are typically situated early in hierarchal networks (Van Essen et al., 1992; Kaas et al., 1999; Kim et al., 2014b), and must rapidly transmit information to other brain regions for higher-order processing. In comparison, secondary/association cortical regions (AudD/AudV, V2, S2 and M2) participate in later stages of hierarchical information processing, and likely integrate many inputs over a longer timeframe. We reasoned that these differences in processing needs may be reflected in a differential balance of perisomatic interneurons. To see if the relative content of perisomatic interneurons differs between primary and secondary areas of the cortex, we calculated the subtractive difference between the average CCK-GABA cell percentage and the average PV-GABA cell percentage (termed D score) in all brain regions studied (Figure 7). Notably, this analysis is distinct from those conducted previously, as it directly compares CCK- and PV-GABA cells to each other and does not include other types of GABA cells.


Comparative density of CCK- and PV-GABA cells within the cortex and hippocampus.

Whissell PD, Cajanding JD, Fogel N, Kim JC - Front Neuroanat (2015)

Perisomatic interneuron balance and its relationship to cortical function. Cell balance was estimated using the delta score (D), which was the subtractive difference between CCK-GABA and PV-GABA cell percentage. Brain regions with D > 0 had more CCK-GABA cells, whereas regions with D < 0 had more PV-GABA cells. Moving right along x-axis of the graph, a decreasing D reflects a relatively increasing PV-GABA cell content. Regions of the primary sensory cortex or primary motor cortex (red) had negative D, indicating relatively higher PV-GABA cell content. Interestingly, secondary regions (green) had less negative D than their primary counterparts, indicating relatively lower PV-GABA cell content. For comparison, other non-motor and non-sensory cortical subregions are included (gray).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585045&req=5

Figure 7: Perisomatic interneuron balance and its relationship to cortical function. Cell balance was estimated using the delta score (D), which was the subtractive difference between CCK-GABA and PV-GABA cell percentage. Brain regions with D > 0 had more CCK-GABA cells, whereas regions with D < 0 had more PV-GABA cells. Moving right along x-axis of the graph, a decreasing D reflects a relatively increasing PV-GABA cell content. Regions of the primary sensory cortex or primary motor cortex (red) had negative D, indicating relatively higher PV-GABA cell content. Interestingly, secondary regions (green) had less negative D than their primary counterparts, indicating relatively lower PV-GABA cell content. For comparison, other non-motor and non-sensory cortical subregions are included (gray).
Mentions: As CCK- and PV-GABA neurons are thought to regulate pyramidal cell activity by distinct mechanisms (Freund, 2003; Freund and Katona, 2007), they may be specialized for certain cortical network activities. Within the cortex, information processing is known to differ substantially between the primary and secondary regions. Primary cortical regions (such as Aud1, V1, S1, and M1) are typically situated early in hierarchal networks (Van Essen et al., 1992; Kaas et al., 1999; Kim et al., 2014b), and must rapidly transmit information to other brain regions for higher-order processing. In comparison, secondary/association cortical regions (AudD/AudV, V2, S2 and M2) participate in later stages of hierarchical information processing, and likely integrate many inputs over a longer timeframe. We reasoned that these differences in processing needs may be reflected in a differential balance of perisomatic interneurons. To see if the relative content of perisomatic interneurons differs between primary and secondary areas of the cortex, we calculated the subtractive difference between the average CCK-GABA cell percentage and the average PV-GABA cell percentage (termed D score) in all brain regions studied (Figure 7). Notably, this analysis is distinct from those conducted previously, as it directly compares CCK- and PV-GABA cells to each other and does not include other types of GABA cells.

Bottom Line: However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale.The reverse trend was observed for PV-GABA cells.The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Toronto, Toronto ON, Canada.

ABSTRACT
Cholecystokinin (CCK)- and parvalbumin (PV)-expressing neurons constitute the two major populations of perisomatic GABAergic neurons in the cortex and the hippocampus. As CCK- and PV-GABA neurons differ in an array of morphological, biochemical and electrophysiological features, it has been proposed that they form distinct inhibitory ensembles which differentially contribute to network oscillations and behavior. However, the relationship and balance between CCK- and PV-GABA neurons in the inhibitory networks of the brain is currently unclear as the distribution of these cells has never been compared on a large scale. Here, we systemically investigated the distribution of CCK- and PV-GABA cells across a wide number of discrete forebrain regions using an intersectional genetic approach. Our analysis revealed several novel trends in the distribution of these cells. While PV-GABA cells were more abundant overall, CCK-GABA cells outnumbered PV-GABA cells in several subregions of the hippocampus, medial prefrontal cortex and ventrolateral temporal cortex. Interestingly, CCK-GABA cells were relatively more abundant in secondary/association areas of the cortex (V2, S2, M2, and AudD/AudV) than they were in corresponding primary areas (V1, S1, M1, and Aud1). The reverse trend was observed for PV-GABA cells. Our findings suggest that the balance between CCK- and PV-GABA cells in a given cortical region is related to the type of processing that area performs; inhibitory networks in the secondary cortex tend to favor the inclusion of CCK-GABA cells more than networks in the primary cortex. The intersectional genetic labeling approach employed in the current study expands upon the ability to study molecularly defined subsets of GABAergic neurons. This technique can be applied to the investigation of neuropathologies which involve disruptions to the GABAergic system, including schizophrenia, stress, maternal immune activation and autism.

No MeSH data available.


Related in: MedlinePlus